Armstrong was such a powerful player, it's said he had to stand 15 feet behind his partners on a 1923 recording session, to avoid upsetting the sound balance.
Recording is handled by a sound crew. in shooting a sound engineer called a mixer watches the action and regulates the volume and the balance of voices.
In the camera recording of TV textbooks, it is necessary to make, in using the TV camera, several adjustments, of which the white balance is especially important.